Semiconductor device and method of manufacturing semiconductor device

• US 20090283823A1
• Filed: 08/08/2008
• Published: 11/19/2009
• Est. Priority Date: 08/10/2007
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Izumi, Naoki
• Granted Patent: US 8,174,066 B2
• Time in Patent Office: Days
• US Class Current: 257/332
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A semiconductor device includes: a semiconductor layer; a first conductivity type region of a first conductivity type formed in a base layer portion of the semiconductor layer; a body region of a second conductivity type formed in the semiconductor layer to be in contact with the first conductivity type region; a trench formed by digging the semiconductor layer from the surface thereof to pass through the body region so that the deepest portion thereof reaches the first conductivity type region; a gate insulating film formed on the bottom surface and the side surface of the trench; a gate electrode buried in the trench through the gate insulating film; a source region of the first conductivity type formed in a surface layer portion of the semiconductor layer on a side in a direction orthogonal to the gate width with respect to the trench to be in contact with the body region; and a high-concentration region of the second conductivity type, formed in the body region on a position opposed to the trench in the direction orthogonal to the gate width, having a higher second conductivity type impurity concentration than that of the periphery thereof.

Claims

1. A semiconductor device comprising:

a semiconductor layer;

a first conductivity type region of a first conductivity type formed in a base layer portion of the semiconductor layer;

a body region of a second conductivity type formed in the semiconductor layer to be in contact with the first conductivity type region;

a trench formed by digging the semiconductor layer from the surface thereof to pass through the body region so that the deepest portion thereof reaches the first conductivity type region;

a gate insulating film formed on the bottom surface and the side surface of the trench;

a gate electrode buried in the trench through the gate insulating film;

a source region of the first conductivity type formed in a surface layer portion of the semiconductor layer on a side in a direction orthogonal to the gate width with respect to the trench to be in contact with the body region; and

a high-concentration region of the second conductivity type, formed in the body region on a position opposed to the trench in the direction orthogonal to the gate width, having a higher second conductivity type impurity concentration than that of the periphery thereof.

2. The semiconductor device according to claim 1, further comprising a channel implant region containing a first conductivity type impurity formed in the body region between the trench and the high-concentration region.

3. The semiconductor device according to claim 1, wherein

the high-concentration region is formed adjacently to the side surface of the trench.

4. The semiconductor device according to claim 1, wherein

the high-concentration region is formed under the source region to be closer to the trench than the center of the source region in the direction orthogonal to the gate width.

5. The semiconductor device according to claim 1, wherein

a contact region of the second conductivity type passing through the source region to come into contact with the body region is formed on the surface layer portion of the semiconductor layer, and

the high-concentration region is formed under the contact region.

6. The semiconductor device according to claim 2, wherein

a contact region of the second conductivity type passing through the source region to come into contact with the body region is formed in the surface layer portion of the semiconductor layer, and

the high-concentration region is formed under the contact region.

7. The semiconductor device according to claim 5, wherein

half of the high-concentration region farther from the trench in the direction orthogonal to the gate width is arranged under the contact region.

8. The semiconductor device according to claim 6, wherein

half of the high-concentration region farther from the trench in the direction orthogonal to the gate width is arranged under the contact region.

9. The semiconductor device according to claim 5, wherein

the high-concentration region is formed in the same width as the contact region in the direction orthogonal to the gate width, and entirely arranged under the contact region.

10. The semiconductor device according to claim 6, wherein

the high-concentration region is formed in the same width as the contact region in the direction orthogonal to the gate width, and entirely arranged under the contact region.

11. A method of manufacturing a semiconductor device, comprising:

a trench forming step of forming a trench by digging a semiconductor layer of a first conductivity type from the surface thereof;

a first implantation step of implanting an impurity of a second conductivity type into the semiconductor layer from the side surface of the trench at an implantation angle inclined with respect to the surface of the semiconductor layer;

a second implantation step of implanting an impurity of the second conductivity type into the semiconductor layer from the surface of the semiconductor layer;

a step of forming a body region of the second conductivity type on a side portion of the trench while forming a high-concentration region of the second conductivity type having a higher second conductivity type impurity concentration than that of the periphery thereof in a position of the body region opposed to the trench in the width direction of the trench by heat-treating the semiconductor layer and diffusing the impurities implanted in the first implantation step and the second implantation step;

a third implantation step of implanting an impurity of the first conductivity type into the periphery of the trench from the surface of the semiconductor layer for forming a source region of the first conductivity type in contact with the body region;

a fourth implantation step of implanting an impurity of the second conductivity type into the source region from the surface of the semiconductor layer for forming a contact region of the second conductivity type passing through the source region to come into contact with the body region;

a step of forming a gate insulating film on the bottom surface and the side surface of the trench; and

a step of burying a gate electrode in the trench through the gate insulating film.

12. The method of manufacturing a semiconductor device according to claim 11, wherein

the impurity of the second conductivity type is implanted at an implantation angle of not less than 18°

with respect to the surface of the semiconductor layer in the first implantation step.

13. The method of manufacturing a semiconductor device according to claim 11, wherein

the impurity of the second conductivity type is implanted into the side surface of the trench and a portion adjacent to the side surface in the first implantation step.

14. The method of manufacturing a semiconductor device according to claim 12, wherein

the impurity of the second conductivity type is implanted into the side surface of the trench and a portion adjacent to the side surface in the first implantation step.

15. The method of manufacturing a semiconductor device according to claim 11, wherein

the impurity of the second conductivity type is implanted while increasing the acceleration thereof stepwise in the first implantation step.

16. The method of manufacturing a semiconductor device according to claim 12, wherein

the impurity of the second conductivity type is implanted while increasing the acceleration thereof stepwise in the first implantation step.